The present invention relates to a double action hydraulic press used for molds that can conduct several types of plastic workings on a plurality of locations of a single material.
As an example of the prior art technology, there is a double action hydraulic press disclosed in Japanese Laid Open Patent Number H10-263888.
In the double action hydraulic press of the prior art, a plurality of inner slide drive cylinders are provided inside an outer slide. In addition, by controlling the flow of oil supplied to each of the inner slide drive cylinders based on some position detection values of the inner slide, the speed, position, and parallelism of the inner slide can be controlled. The outer slide conducts a first molding, and the inner slide conducts a second molding via a push pin, which is a means for transferring pressure.
However, with the double action hydraulic press of the prior art, when controlling the speed, position, and parallelism of the inner slide, the flow of oil supplied to each of the inner slide drive cylinders is controlled separately. As a result, the rod positions among the inner slide drive cylinders can be easily shifted, and as a result, the control of the inner slide becomes difficult. Furthermore, there is a plurality of inner slide drive cylinders provided inside the outer slide. As a result, the space inside the outer slide must be large, and miniaturization of machines becomes difficult.
Furthermore, with the double action hydraulic press of the prior art, there is no measure to combat against the so-called breakthrough phenomenon where the outer slide or the inner slide descends below the bottom dead center during punching.
Therefore, when punching is conducted with the double action hydraulic press of the prior art, noise and vibrations due to breakthrough phenomenon is generated, and as a result, there are negative effects on the product precision and on the environment.
Furthermore, the push pins are supported in a freely rising and falling manner by a sliding member provided on the lower surface of the outer slide, but the lower surface plate of the outer slide can not be removed. As a result, the operation for exchanging the push pins, which occurs in conjunction with the changing of the mold, becomes extremely complicated.
An object of the invention is to provide a double action hydraulic press, in which the changing operation for the push pins, which occurs in conjunction with mold changes, is easy.
A further object of the invention is to provide a double action hydraulic press, wherein costs are reduced due to miniaturization of construction members. In addition, the speed, position, and parallelism of the inner slide can be controlled easily with high precision.
A further object of the present invention is to provide a double action hydraulic press, in which breakthrough phenomenon during punch working is reduced.
The invention in one embodiment is a double action hydraulic press, the double action hydraulic press having a separate drive source for each slide, and comprising: an outer slide, which is guided in a freely rising and falling manner by an outer slide guide provided on a column; an inner slide, which is guided in a freely rising and falling manner by an inner slide guide provided inside the outer slide; an outer slide drive cylinder, which is provided on a press crown part, has an end of a rod connected to the outer slide, and drives the outer slide; an inner slide drive cylinder, which is provided in the outer slide, has an end of a rod connected to the inner slide, and drives the inner slide; a die plate, which is provided in a detachable manner on a lower surface of the outer slide; a push pin, which is supported in a freely rising and falling manner by a sliding member provided on the die plate and is provided with a spring between a collar part and a die plate upper surface.
With this embodiment, the outer slide and the inner slide, which is provided inside the outer slide, each have a separate drive source. As a result, several types of plastic working can be conducted on a single material. Furthermore, the die plate, which is provided on the outer slide lower surface and is provided with push pins, is detachable. Therefore, when exchanging the push pins in conjunction with an exchange in molds, the die plate, which is provided with the push pins, is exchanged. Furthermore, by altering the shape of the die plate according to the mold, it can correspond to various dies.
The above described embodiment additionally, can comprise: a plurality of the outer slide drive cylinders and the inner slide drive cylinders; a plurality of outer slide position detection devices, which detect the positions of the outer slides; an outer slide control device, which, by controlling the flow volume supplied to the outer slide drive cylinder based on the detection values detected from the outer slide position detection devices and a pre-set value, controls the outer slide so that its speed, position, and parallelism are maintained; a plurality of inner slide detection devices, which detect the positions of the inner slides; an inner slide control device, which, by controlling the flow volume supplied to the inner slide drive cylinder based on the detection values detected from the inner slide position detection devices and a pre-set value, controls the inner slide so that its speed, position, and parallelism are maintained.
With the above double action hydraulic press, a plurality of outer slide drive cylinders is provided, and based on the values detected by the outer slide position detection devices and a pre-set value, the flow of oil supplied to each of the cylinders can be controlled. As a result, the speed, position, and parallelism of the outer slide can be controlled. Furthermore, a plurality of inner slide drive cylinders is provided inside the outer slide, and by controlling the flow of oil supplied to each of the cylinders, the speed and position of the inner slide can be controlled, and the parallelism can be maintained.
The double action hydraulic press can include in addition: an equalize shaft, which passes through the outer slide and the inner slide, is provided at both ends with a pinion, and is supported by a bearing provided on the inner slide; a rack, which is provided on the outer slide and engages with the pinion.
In the invention, the equalize shaft is passed through the outer slide and inner slide and is supported by a bearing provided on the inner slide. A pinion is provided on both ends of this equalize shaft, and a rack, which engages with said pinion, is provided on the outer slide. For example, when the equalize shaft passes through in the front to back direction, the speed and the position of the inner slide in the front to back direction is synchronized, and as a result, the parallelism of the inner slide in the front to back direction can be maintained.
Furthermore, because the parallelism of the inner slide can be maintained by mechanical construction members, the number of inner slide drive cylinders can be reduced.
For example, the parallelism in the left to right direction is controlled by the inner slide drive cylinder, and the parallelism in the front-back direction is maintained by a mechanical construction member of an equalize shaft. In this situation, the number of inner slide drive cylinders which are necessary is two. As a result, compared to when three or greater inner slide drive cylinders are necessary, the control is greatly improved because there are fewer things that need to be controlled. In addition, when the number of inner slide drive cylinders is reduced, the outer slide can be miniaturized, and this can result in miniaturization of the overall machine.
The double action hydraulic press can comprise in addition: a damper cylinder, which is provided on the bottom of the inner slide and is provided with a flow metering valve on a hydraulic circuit which is connected with the cylinder.
With this, there is provided a damper cylinder which descends while in contact with the inner slide lower surface. When this occurs, because the oil volume which flows out of the cylinder is restricted by a flow metering valve in a hydraulic circuit, there is high pressure inside the cylinder. As a result, even when punching with the inner slide and breakthrough phenomenon occurs, the rapid descent of the inner slide can be reduced. As a result, the work environment and product precision can be improved.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.